Machine for winding high-voltage electrical bushings

ABSTRACT

A machine for manufacturing high-voltage electrical bushings of the condenser type comprises a system of rolls supporting a rotatably driven conductor tube which serves as the core on which a paper web pulled from a supply roll is wound to form the body of the bushing, the roll system being displaceable to accommodate the change in diameter of the bushing as it is progressively enlarged. Rolls of aluminum foil arranged in longitudinally spaced, overlapped relation supply edge-overlapped webs of selectable overall width which are inserted into the paper being wound, at the required different diameters within the bushing body, to form corresponding radially spaced cylindrical capacitive control shields. Rotary knives are also arranged to operate along each edge of the paper web to slit the web as it is drawn off the supply roll and these knives are shifted laterally of the web and independently of each other at a speed coordinated to the winding speed of the bushing body so as to develop a desired conical contour at each end of the completed bushing body when the excess edge material cut off by the knives is removed.

United States Patent [191 Rossi et al.

[ 1 June 5, 1973 [54] MACHINE FOR WINDING HIGH- VOLTAGE ELECTRICAL BUSHINGS [73] Assignee: Micafil A.G., Zurich, Switzerland [22] Filed: Sept. 2, 1971 [21] App]. No.: 177,371

[30] Foreign Application Priority Data Primary Examiner-George F. Mautz Assistant ExaminerEdward J. McCarthy Attorney-Pierce, Scheffler & Parker [57] ABSTRACT A machine for manufacturing high-voltage electrical bushings of the condenser type comprises a system of rolls supporting a rotatably driven conductor tube which serves as the core on which a paper web pulled from a supply roll is wound to form the body of the bushing, the roll system being displaceable to accommodate the change in diameter of the bushing as it is progressively enlarged. Rolls of aluminum foil arranged in longitudinally spaced, overlapped relation supply edge-overlapped webs of selectable overall width which are inserted into the paper being wound, at the required different diameters within the bushing body, to form corresponding radially spaced cylindrical capacitive control shields. Rotary knives are also arranged to operate along each edge of the paper web to slit the web as it is drawn off the supply roll and these knives are shifted laterally of the web and independently of each other at a speed coordinated to the winding speed of the bushing body so as to develop a desired conical contour at each end of the completed bushing body when the excess edge material cut off by the knives is removed.

10 Claims, 9 Drawing Figures PATENTEDJUH 5197a SHEET 2 BF 3 Fig. 4

PAIENTEDJUH 5|973 3.737.116

smzn 30F a MACHINE FOR WINDING HIGH-VOLTAGE ELECTRICAL BUSHINGS This invention relates to an improvement in winding machines for manufacturing high-voltage electrical bushings of the so-called condenser type incorporating shields of conductive material to establish capacitive control of the voltage gradient, and more particularly to an improved machine structure capable of produc ing condenser bushings as long as meters.

Winding machines for producing condenser bushings up to a maximum length of 5 meters are already known but these involve relatively great technical expenditure. A principal object of this invention is to provide an improved winding machine which is not only capable of winding condenser bushings up to twice the length heretofore considered practical but which is far more simple, from a viewpoint of construction, and hence correspondingly less expensive to produce.

More particularly, in accordance with the invention, as will be hereinafter developed in more detail, the winding machine is composed of simple structural components, the rolls which support the bushing for rotation about its axis as it is being formed from a paper web, as well as a pre-heating roll to heat the paper material before being wound are not machined, and the tubular core of conductive material on which the paper and condenser shields are wound is driven in rotation by means of a self-locking mandrel which is advanced up to the center of the tube.

The foregoing as well as other objects and advantages inherent in the improved winding machine structure will become more apparent from the following detailed description of a preferred construction thereof and the accompanying drawings which illustrate it, and wherein:

FIG. 1 is a somewhat schematic view of the essential components of the machine in side elevation;

FIG. 2 is an elevation taken at a right angle to FIG. 1 and which illustrates the supporting arrangement for the supply rolls of metallic conductive sheet material, preferably aluminum, which is fed into the machine at the proper times and locations to form and distribute the condenser shields throughout the body of the bushmg;

FIG. 3 is a central longitudinal section of a completed bushing;

FIG. 4 is a transverse view showing the selftensioning paper roll holder;

FIG. 5 is a sectional view of the paper tensioning device;

FIG. 6 is a schematic view of the system for circulating warming oil through the various rolls which contact the paper web;

FIG. 7 is a view of the cutting device by which the side edges of the paper web are progressively trimmed;

FIG. 8 is a view of the cable device for smoothing the aluminum web inserts; and

FIG. 9 is a schematic view of the measuring arrangement provided for determining the diameter of the bushing as it is being wound.

With reference now to FIG. 1, which depicts a partially completed bushing, it will be seen that the bushing 6 is supported for rotation about its axis by a system of three rolls, the rotational axes of which are equally spaced (120 apart) about the axis of the bushing. Included are two lower rolls 1 and 2 whose rotational axes are located in a common horizontal plane and an upper roll 3, carried at the free end of a pivotally mounted support arm 3a, and which is filled with lead shot so as to rest its deadweight on the condenser body 6 as it is being wound. A cable hoist line (not illustrated) drawn by an electric motor can be attached to the support arm 3a to raise and release the latter from the bushing body after it has been completed so as to facilitate its removal from the machine.

The front, lower roll 1, over which the paper web 8 is fed to the bushing body as it is being wound is mounted for rotation about an axis which is stationary. THe other lower roll 2, however, is so mounted that its axis of rotation can be shifted rearwardly, in the direction away from roll 1 as the diameter of the bushing 6 grows during the winding process.

The core for the bushing is a tubular conductor 5 which is rotated about its axis by a drive shaft 4 from the output of a variable speed transmission powered by an electric motor, not illustrated. Drive shaft 4 extends into conductor 5 from one end thereof up to the middle of the conductor, and the end of the shaft terminates in an automatically expandable mandrel 7 which frictionally engages the interior wall of conductor 5 to provide the driving connection.

The web of paper from which the bushing is formed is drawn from a supply roll 9 and passes over a preheating roll 10 and roll 1 to the conductor tube 5. The paper supply roll 9 is also provided with an automatically operable mandrel structure 11 which is mounted in bearings at both ends and coupled to a disc brake at each end. Braking of the paper supply roll 9 is established by means of a compressed air system, not illustrated, which is controlled by a reducing valve.

The pre-heating roll 10 is supported by bearings which are displaceable in the pull direction of the paper and which adapt themselves to movement of the paper web by means of cup springs 12 associated with the bearings.

The frame of the machine consists of a suitable arrangement of unmachined structural parts, namely, a system of double-T girders arranged at right angles to each other, and the rolls 1, 2 and 10 are likewise unmachined. Support blocks 14 with two rolls 17 which engage and support the front roll 1 are mounted in a stationary manner on the upper longitudinally extending girder structure, and similar support blocks 16 with support rolls 17 are provided for the rear roll 2. However, as previously indicated, in order that roll 2 may shift backwards as the diameter of the bushing body 6 grows, the support blocks 16 are arranged for horizontal displacement on plates 15 of a hardened synthetic resin, and are displaced parallel by means of a screw spindle and a common, motor-driven worm shaft, not illustrated.

Rolls 1, 2 and 10 are heated by means of a thermostatically controlled heat transfer oil, which is heated in an oil heater set up outside of the machine and pumped through the interior of the rolls by means of a circulation system in which the rolls 1, 2 and 10 are connected hydraulically in series, illustrated in FIG. 6.

Metallic foil 19, preferably aluminum is used to establish the capacitive control shields. As shown in FIG. 2, the foil is drawn from two parallel rows of axially spaced supply rolls 18a, 18b and the rolls of the two rows are staggered axially by suitable adjustment of the foils in an axial direction so as to provide a certain amount of edge overlap. As is the practice in forming condenser bushings, the cylindrical capacitive shields are distributed throughout the body of the bushing in a radially spaced manner, and the axial lengths of the shields diminish progressively in a radially outward direction. Thus, when the first shield is to be applied, all of the aluminum webs 19 will be drawn down simultaneously, introduced into the paper 8 being wound, and simultaneously cut off by means of a movable knife 20 mounted on the machine, after one revolution of the bushing body. As the diameter of the bushing body grows and reaches the next larger diameter where the next shield is to be introduced, and which will have a shorter axial length than the preceding one, the two outermost rolls of the rows 18a, 18b are correspondingly shifted by means of a hand actuated device and one roll is removed when no longer required.

Between the pre-heating roll and front roll 1, FIG. 6, two mutually independent cutting devices 21 are provided, at each side of the paper web, each such device including a pair of motor-driven rotary knives which serve to continuously trim the side edge of the paper web. Since condenser bushings are made with different configurations, the cutting devices 21 are arranged to be shifted independently of each other in a direction transverse to the direction of travel of the web, and at desired rates of movement as a function of the rotational speed of the conductor tube 5 so as to develop any particularly desired configuration, e.g. conical. Each cutting device 21 cuts out a paper strip, whereby removal of the excess internally coned paper bodies 22,23 shown in FIG. 3 after completion of the winding operation is facilitated.

In order to make certain that prior to insertion in the paper, the aluminum webs 19 lie smoothly on a guide plate 24 which is movable to the insertion position shown in broken lines, there is provided a cable 25., e.g. hemp rope actuated by pneumatic pressure cylinders which impinges upon the webs so as to make them lie flat on the guide plate.

In order to enable one to determine the correct diameter of the bushing body at which each aluminum shield is to be inserted, there is provided an electrical diameter-measuring device which functions on the principle that the length of the paper which runs during each revolution of the bushing body being wound is measured in terms of electrical pulses which are then converted into terms of diameter by means of a computer, and indicated. This diameter-measuring device as shown in FIG. 9 includes a scanning roll 29 in contact with and driven by the paper web 8, the roll 29 being coupled to and driving an electrical pulse generator 26 by means of a belt transmission 30. The electrical pulses are amplified in amplifier 2'7 and then fed to the computer 28.

We claim:

1. In a machine for manufacturing high-voltage electrical bushings of the condenser type by winding a paper web on a tubular electrical conductor which serves as a core and inserting capacitive control shields within the body of the bushing as it is being wound on the core, the combination comprising a support frame, a roll assembly on which said tubular electrical conductor is supported for rotation about its axis, said roll assembly comprising at least two roll means initially engageable with and supporting said tubular conductor, said roll means being mutually adjustable relative to said tubular conductor to maintain support therefor as the diameter of the bushing becomes progressively greater during the winding, means for feeding a web of paper to said tubular conductor to be wound thereon, a drive for said tubular conductor, said drive including a drive shaft extending within said tubular conductor and terminating in a mandrel structure engageable with the internal surface of said tubular conductor, and rolls of an electrically conductive metallic foil arranged transversely of said paper web in longitudinally spaced, edge-overlapped relation to supply edge-overlapped foil webs of selectable overall width for insertion into the paper web being wound at different diameters within the bushing body to form said capacitive control shields.

2. A machine as defined in claim 1 for manufacturing high-voltage electrical bushings of the condenser type wherein said roll assembly for supporting said tubular electrical conductor and the paper wound thereon is comprised of two lower rolls arranged for relative displacement away from each other, and an upper roll intermediate said lower rolls and which is adapted to ride on top of the paper as it is being wound.

3. A machine as defined in claim 2 for manufacturing high-voltage electrical bushings of the condenser type wherein said upper roll is rotatably mounted at the free end of a pivotally mounted arm secured to said frame.

4. A machine as defined in claim 1 for manufacturing high-voltage electrical bushings of the condenser type wherein said means for feeding a paper web to said tubular conductor for winding thereon includes a supply roll of the paper, and means supporting said supply roll for rotation on its axis including an automatically engageable mandrel mounted in bearings.

5. A machine as defined in claim 1 for manufacturing high-voltage electrical bushings of the condenser type wherein said means for feeding a paper web to said w bular conductor for winding thereon includes a supply roll of the paper mounted for rotation about its axis and which further includes a pre heating roll located between said paper supply roll and said roll assembly over which said paper web passes, and means for heating said pre-heating roll and roll assembly by passing a heated fluid therethrough.

6. A machine as defined in claim 5 for manufacturing high-voltage electrical bushings of the condenser type wherein said pre-heating roll is mounted on displaceable bearings for rotation about its axis, and spring means cooperable with and acting upon said bearings in the direction of the pull of the paper web.

7. A machine as defined in claim 1 for manufacturing high-voltage electrical bushings of the condenser type and which further includes cutting means allocated respectively to opposite sides of said paper web for progressively trimming the edges thereof in the direction of the center of the web prior to winding so as to progressively narrow the width of the web as finally embodied in the finished bushing.

8. A machine as defined in claim 7 for manufacturing high-voltage electrical bushings of the condenser type wherein said cutting means comprises two mutually independent cutting devices located on each side of said paper web.

9. A machine as defined in claim 1 for manufacturing high-voltage bushings of the condenser type and which further includes a plate for guiding the edgeoverlapped webs of metallic foil to the paper web and scanning roll in contact with and driven by the paper web, an electrical pulse generator driven by said scanning roll and a computer connected to the output of said pulse generator for converting said pulses into terms of displayed bushing diameter. 

1. In a machine for manufacturing high-voltage electrical bushings of the condenser type by winding a paper web on a tubular electrical conductor which serves as a core and inserting capacitive control shields within the body of the bushing as it is being wound on the core, the combination comprising a support frame, a roll assembly on which said tubular electrical conductor is supported for rotation about its axis, said roll assembly comprising at least two roll means initially engageable with and supporting said tubular conductor, said roll means being mutually adjustable relative to said tubular conductor to maintain support therefor as the diameter of the bushing becomes progressively greater dUring the winding, means for feeding a web of paper to said tubular conductor to be wound thereon, a drive for said tubular conductor, said drive including a drive shaft extending within said tubular conductor and terminating in a mandrel structure engageable with the internal surface of said tubular conductor, and rolls of an electrically conductive metallic foil arranged transversely of said paper web in longitudinally spaced, edge-overlapped relation to supply edge-overlapped foil webs of selectable overall width for insertion into the paper web being wound at different diameters within the bushing body to form said capacitive control shields.
 2. A machine as defined in claim 1 for manufacturing high-voltage electrical bushings of the condenser type wherein said roll assembly for supporting said tubular electrical conductor and the paper wound thereon is comprised of two lower rolls arranged for relative displacement away from each other, and an upper roll intermediate said lower rolls and which is adapted to ride on top of the paper as it is being wound.
 3. A machine as defined in claim 2 for manufacturing high-voltage electrical bushings of the condenser type wherein said upper roll is rotatably mounted at the free end of a pivotally mounted arm secured to said frame.
 4. A machine as defined in claim 1 for manufacturing high-voltage electrical bushings of the condenser type wherein said means for feeding a paper web to said tubular conductor for winding thereon includes a supply roll of the paper, and means supporting said supply roll for rotation on its axis including an automatically engageable mandrel mounted in bearings.
 5. A machine as defined in claim 1 for manufacturing high-voltage electrical bushings of the condenser type wherein said means for feeding a paper web to said tubular conductor for winding thereon includes a supply roll of the paper mounted for rotation about its axis and which further includes a pre-heating roll located between said paper supply roll and said roll assembly over which said paper web passes, and means for heating said pre-heating roll and roll assembly by passing a heated fluid therethrough.
 6. A machine as defined in claim 5 for manufacturing high-voltage electrical bushings of the condenser type wherein said pre-heating roll is mounted on displaceable bearings for rotation about its axis, and spring means cooperable with and acting upon said bearings in the direction of the pull of the paper web.
 7. A machine as defined in claim 1 for manufacturing high-voltage electrical bushings of the condenser type and which further includes cutting means allocated respectively to opposite sides of said paper web for progressively trimming the edges thereof in the direction of the center of the web prior to winding so as to progressively narrow the width of the web as finally embodied in the finished bushing.
 8. A machine as defined in claim 7 for manufacturing high-voltage electrical bushings of the condenser type wherein said cutting means comprises two mutually independent cutting devices located on each side of said paper web.
 9. A machine as defined in claim 1 for manufacturing high-voltage bushings of the condenser type and which further includes a plate for guiding the edge-overlapped webs of metallic foil to the paper web and a cable engageable with said foil webs to cause the latter to lie smoothly on the surface of said guide plate.
 10. A machine as defined in claim 1 for manufacturing high-voltage bushings of the condenser type and which further includes means for measuring the diameter of the bushing as it is being wound comprising a scanning roll in contact with and driven by the paper web, an electrical pulse generator driven by said scanning roll and a computer connected to the output of said pulse generator for converting said pulses into terms of displayed bushing diameter. 